The Pontifical Gregorian University in Rome currently has a philosophy department that endorses both biological and psychological
evolution, an endorsement of matter and form, and the consequent endorsement of potency and act.1 Nevertheless,
the emphasis of the current course is more on the biological fact of evolution than on the deeper philosophical explanation
of the possibility of evolution, except for the arguments favoring its final causality.

The Scholastic2 philosophers have generally followed Aristotle3 and Aquinas in the endorsement of
the theory of Hylemorphism,4 that all mobile creatures are composed of act and potency.5 Since Evolution
involves the change of creatures, act and potency are both necessary for an adequate philosophical explanation of evolution.

Evolution is a process, so some act and potency, and privation, are involved. Observation reveals that matter is involved
with evolution, and the Neo-Scholastic views matter as the principle of individuation, which determines "this" creature and
its species.6 Matter, however, is potency and needs to form to educe it to act. Substance is involved in the evolutionary
process, since evolution moves from one substance (species) to a new substance (new species). Accidents are involved in evolution,
since it appears that some dispositions are needed in the matter prior to any substantial change. Further, accidents are important
for observation of any evolution, since the accidents, not the substance, are what is visible; for example, when the tall
white man is seen, the accidents (tall, white) are seen directly, and the substance (man) is inferred from the accidents and
dispositions. Therefore, in order to give a philosophical explanation of evolution, all these elements must somehow be accounted
for. This is done by the hylemorphic system.7